584 CHILL 
varieties on the mountains contained a kind of jasper in broad imper- 
fect veins, resulting apparently from the action of heat. 
The stratification of the rock is often distinct, but observations on 
this point should be extensive to be of much value. 
No fossils were observed excepting lignite. This occurs in the 
Jaguel Valley in a fine conglomerate, consisting of argillaceous and 
porphyritic pebbles of different colours, half an inch in diameter and 
smaller. The locality is situated high up on a steep acclivity, bound- 
ing the valley on the south, and according to our estimate, is four 
thousand five hundred feet above the sea. ‘The place was too much 
buried in soil to be uncovered in the few hours of our visit to it; but 
specimens lay around, some of which were imperfectly bituminous 
coal, and others were very argillaceous. Some coarser varieties con- 
tained thin chalcedonic seams. A few specimens of the conglomerate 
were found with the lignite imbedded. ‘The purer lignite burnt 
freely with an empyreumatic odour. 
The silicified wood of the Andes is said to occur in a similar con- 
glomerate; but whether it belongs to a single epoch, or, as is more 
probable, to different periods, has not been satisfactorily determined. 
It occurs in the form of agate, jasper and hornstone, and generally re- 
tains well the texture of the original wood. ‘The external surface is 
often bleached by exposure, and sometimes in this way is made to 
resemble bark. One specimen obtained had been bored by some in- 
sect or worm before it was petrified. About two miles from the Post 
House, eight miles east of Valparaiso, there are numerous fragments 
of silicified wood, and among them part of a trunk of a tree, two feet 
in diameter and fifteen inches long. From their position, it was evi- 
dent that they had been transported to their present place since they 
were silicified. A single specimen of similar fossil wood was met 
with on the hills just south of the Concon, twenty-five miles north of 
Valparaiso. 
The copper mines of Chili are connected with the dikes and sedi- 
mentary rocks of the Andes. In our hasty glance at the copper mine 
of the Jaguel Valley, we observed that the vein occurred in the clay- 
stone or sedimentary rocks, near an intersection of it with a com- 
pact clinkstone, and passed also into the clinkstone. ‘The dike is 
about six feet wide, and runs nearly northeast and southwest. The 
claystone has a dark greenish-brown colour, and resembles a wacke. 
